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Air Handlers hooked to hot water boiler

Discussion in 'Residential' started by kena, Jun 10, 2017.

  1. kena

    kena New Member

    Messages:
    711
    I may have asked this question is some way before... so sorry if I'm repeating myself.

    If you have an air handler for hydro air (heat and coiling), what's the best way to wire it with the boiler.
    The reason I ask is because I'm used to having the thermostat start the air handler blower first, then the boiler is called for heat. I started a job where the air handler was already hooked up to HTP on demand boiler via Taco control board.

    So... I would normally wire the therm to the air handler, then to the Taco board so that it would call for heat. In this case... they have it wired in such a way that the circulator fires first, then the air handler comes on after delay. However... this is zone two, and if I shut heat off at the therm, it is still calling. I disconnected all the wires off the heat exchanger and it shows it's still calling. I'm guessing they have the wiring all messed up. I haven't had time yet to trace it all out. My big question is just do you guys fire the air handler first so the blower is already running before the boiler fires. That's the only way I've done it. These guys who wired it are electricians who don't do low voltage. So they don't have a clue... Any suggestions?
     
  2. pecmsg

    pecmsg Junior my ASS

    Messages:
    19,862
    Location:
    Eastern LI
    I get the H W too the coil then bring on the fan.
    Avoids the cool / cold blast of air to start
     
  3. kena

    kena New Member

    Messages:
    711
    So you would wire therm to the Taco board which would call for heat on the on demand boiler, then from the Taco board to the air handler? There's a delay on the air handler so there would be hot water already flowing through the heat exchanger.
    That makes sense too. Somehow they have this all screwed up. At first glance, I couldn't see what was calling for heat on zone 2. I unhooked the therm and air handler. It was still calling and hot water was circulating through the air handler. Sounds like tracing it out and possible rewiring.
     
  4. kena

    kena New Member

    Messages:
    711
    The way my electrician has done my jobs is wire it so the air handler has to be on for the boiler to kicks on.
     
  5. pecmsg

    pecmsg Junior my ASS

    Messages:
    19,862
    Location:
    Eastern LI
    Taco makes a Control that sends the signal to the boiler and has a sensor to delay the fan. Can't think of the #
     
  6. chesty puller

    chesty puller New Member

    Messages:
    31
    You don't want cold air blowing through the space, pumps come on when boiler reaches temperature, then you bring air on.. that is how it should work.

    Sent from my Z812 using Tapatalk
     
  7. pecmsg

    pecmsg Junior my ASS

    Messages:
    19,862
    Location:
    Eastern LI
  8. jettinvr6sc

    jettinvr6sc New Member

    Messages:
    633
    Location:
    Long Island NY
    I just throw an aqua stat (Honeywell L6006C1018) set to 120 degrees on the return of the hwc. I use that to bring the fan on.

    Sent from my SM-N910T using Tapatalk
     
    Last edited: Jun 10, 2017
  9. kena

    kena New Member

    Messages:
    711
    Can you use this in conjunction with another Taco control that handles the indirect water heater? So if I used this Taco control, I would use one for each air handler.... I have two.

    I know they have the Taco control set to priority for the indirect water heater. I wonder if the fact zone 2 keeps calling is it freezing up and staying on. I've never waited an hour to see if it stops calling.
     
  10. pecmsg

    pecmsg Junior my ASS

    Messages:
    19,862
    Location:
    Eastern LI
    Depending on the model yes.
     
  11. kena

    kena New Member

    Messages:
    711
    Well, the only other thing besides the two air handlers is an indirect HTP 80 gallon tank with Aquastat. So if I use two of these for the air handlers, I only need to deal with the HTP tank
     
  12. Zman

    Zman Hanging by a Thread

    Messages:
    500
    Location:
    The "I know a Guy" State
    First Company Hydro's? Zone valves with 1 circulator at the Boiler,or 3 circulators? What kinda Boiler,large mass,tripple pass or Condensing 90+?
     
  13. LemonWizard

    LemonWizard Blinky Lights Wizard

    Messages:
    1,971
    Location:
    Ohighyo
    Start circulation pump.
    Prove flow. (Optional)
    Start boiler.
    Prove water leaving water coil is hot enough for heating.
    Start fan.

    Also a good idea to have freeze protection that will lock out the blower if airstream exiting the heating coil is too cold.
     
  14. pecmsg

    pecmsg Junior my ASS

    Messages:
    19,862
    Location:
    Eastern LI
    Freeze protection should be when temperature gets near freezing run circulator
     
  15. LemonWizard

    LemonWizard Blinky Lights Wizard

    Messages:
    1,971
    Location:
    Ohighyo
    Yes I meant to put that as well.
    Definately need to stop drawing near freezing air across a water coil if its not got heat in it though.
     
  16. knave

    knave Out for a rip

    Messages:
    7,327
    Location:
    Out for a rip
    Ken

    What's the application?

    Resi?

    Commercial?

    Any fresh air?